1. Field of the Invention
This invention relates to a composite helmet comprising a helmet body composed of a plastic or a metal and a hollow molding having a truncated pyramid or cone shape mounted or fixed detachably or undetachably on the outer surface of the helmet body so as to make the external shape of the hollow molding similar to the external shape of the helmet body, and if necessary, ceramic chips are fixed on the whole or a part of the surface of the hollow molding, said hollow molding being freely detachable, whereby when an object coming flying at a high speed hits against the helmet, substantially all the energy of the object coming flying is absorbed by the partial breakage of the hollow molding having a truncated pyramid or cone shape or by the partial breakage of the ceramic or both the ceramic and the hollow molding to effectively prevent the helmet body from being impaired and bulged inside, and hence, said composite helmet has good impact resistance against an object coming flying at a high speed.
Moreover, this invention relates to a composite helmet uniformalized in thickness, lessened in volume and weight-saved by allowing the above hollow molding to have an external shape extremely similar to the external shape of the helmet body, that is, to have a truncated, bisymmetric pyramid or pseudocone shape.
2. Statement of the Related Art
It is a well-known fact that a helmet can serve as an impact resistant body against an object falling down from a high place or an object coming flying. However, when the impact force is large, it is impossible in many cases that the helmet, when used alone, softens said impact force.
It is now a known fact that, in general, an impact resistant body against an object falling down from a high place or an object coming flying at a high speed is provided by bonding ceramics to a plate of a high-strength fiber-reinforced plastic (referred to hereinafter as ACM). Moreover, a technique for bonding a ceramic plate having a curved surface to an ACM plate having a curved surface has been used in Japan and abroad in the field of a bullet-resistant plate for a bulletproof vest or the like. The present applicant filed a Japanese patent application (JP-A-8-192,497) as to this technique.
However, a helmet has a three-dimensional curved outer surface which varies continuously, and when ceramic chips are fixed directly on said outer surface, it is desirable to make the back surface shapes of the ceramic chips identical with the outer surface shape of the helmet. However, it is actually impossible in the economical and technical aspects to prepare a ceramic molding having such a shape. On the other hand, even when it is intended to prepare several kinds of ceramic chips so as to fit the outer surface of the helmet and fix them on the helmet, such portions that the ceramic chips do not fit the outer surface of the helmet are caused on the helmet and spaces are formed among the ceramic chips and between the ceramic chip and the helmet, resulting in decrease of bullet resistance. Therefore, it is necessary to improve this point. Furthermore, once ceramic chips are fixed on the helmet, it is difficult to remove the ceramic chips, and even when there is no risk of an object falling down from a high place or an object coming flying at a high speed at all, it has been always necessary to wear a heavy weight ceramic-fixed helmet.
The present inventors have accomplished a composite helmet excellent in impact resistance by mounting or fixing a hollow molding having an external, truncated pyramid or cone shape on the outer surface of a helmet body composed of a plastic or a metal, and, if necessary, further fixing ceramic chips on the whole or a part of the surface of the hollow molding. That is, the composite helmet has no spaces among the ceramic chips and between the ceramic chip and the hollow molding and in the composite helmet, even when the helmet receives a strong impact force, the impact force applied to the helmet body composed of a plastic or a metal is softened because the breaking energy thereof is transmitted to the helmet body through the hollow molding or the ceramic-fixed hollow molding, and simultaneously the helmet is effectively prevented from being bulged inside. In addition, the present inventors have accomplished a weight-saved composite helmet by using a hollow molding having an external, truncated, bisymmetric pyramid or pseudocone shape for making the external shape of the hollow molding more approximate to the external shape of the helmet body.
According to this invention, there is provided a composite helmet which comprises a helmet body composed of a plastic or a metal and a hollow molding having an external, truncated pyramid or cone shape mounted or fixed detachably or undetachably on the outer surface of the helmet body.
According to this invention, there is further provided a composite helmet which comprises a helmet body composed of a plastic or a metal and a ceramic-fixed hollow molding having an external, truncated pyramid or cone shape mounted or fixed on the outer surface of the helmet body, wherein the ceramic chips are fixed on the whole or a part of the surface of the hollow molding.
The composite helmet of this invention is preferably characterized in that the hollow molding is of such a type that at least two kinds of starting hollow moldings having different truncated pyramid or cone shapes are put one on another and integrally bonded to one another so as to make the integrated boundary surface smooth and make the external shape of the resulting hollow molding more similar to the external shape of the helmet body. Moreover, the other preferable composite helmet of this invention is characterized in that the above hollow molding is of such a type that in order to make the external shape of the resulting hollow molding much more similar to the external shape of the helmet body, a part of the starting hollow molding is cut off vertically to the base of the pyramid or cone in a certain width along the center line of the base so that the center line comes to the center of the width and the two divisions remaining after the cutting off are integrally bonded to each other to allow the resulting hollow molding to have a truncated, bisymmetric, pyramid or pseudocone shape.